The proposed research aims at development of implanted electrode array for stimulation of the auditory nerve in persons with total endorgan deafness -- a hearing prosthesis. Various metals and semiconductors will first be evaluated electrochemically for ionization characteristics compatible with long-term tissue stimulation. Optimal selections will be tested in animals for extended periods. A multi- electrode array of a successful electrode material will then be fabricated and again tested in animals, along with simultaneously developed electronics for passive transfer of stimulus current across the skin. If successful, this electrode and stimulus system will be placed in the auditory nerves of human volunteers who are deaf in that ear. The range will be evaluated, and external electronics modified accordingly. If the perceptual range seems adequate, a wearable (portable) acoustic-to-electrical stimulus transducer will be developed for longer term perceptual and auditory learning studies.